First, the key is the private property of the company, and the company gives it to you. You have the right to use it, but you have no ownership. You have no right to lend it to others unless the company lets you lend it to others. Secondly, the key is a very important thing, it opens the door of the company, or a drawer for storing important documents or things. If you lend it out rashly, you will bear legal responsibility in case something disappears.